MT1-MMP deficiency prevents HIF-mediated transcription of nichefactors. (A) FIH-1 expression in subcellular fractions was analyzed by Western blotting. α/β tubulin and integrin-β1 are representative cytosolic and membrane proteins, respectively. (B) Representative images of immunofluorescent staining of nestin (green fluorescence) and FIH-1 (red fluorescence) in BM sections derived from MT1-MMP^+/+ and MT1-MMP^−/− mice. The arrows indicate nestin⁺/FIH-1 cells. Nuclei were counterstained with DAPI (blue; bars, 100 μm). (C) Representative images of immunofluorescent staining of HIF-1α (green fluorescence) in BM cells derived from MT1-MMP^+/+ and MT1-MMP^−/− mice. Nuclei were counterstained with DAPI (blue). (D-I) KitL, SDF-1α and IL-7 gene expression in (D-F) MS-5 cells overexpressing FIH-1, and (G-I) in MT1-MMP–deficient MS-5 cells with or without FIH-1 knockdown as analyzed using real-time PCR. The results are expressed relative to expression of a β-actin, which was set at 1.0. Data shown are representative of 3 to 4 independent experiments.